Yes, you can register for GST/HST after crossing the $30,000 threshold — but late registration comes with consequences. The CRA can assess GST/HST owing on all taxable supplies made from the date you should have registered, even if you never collected it from clients.
What Happens When You Register Late
Once you cross the $30,000 threshold, you have 29 days to register. If you miss this window:
- Your effective registration date is deemed to be the date you should have registered — the date of the sale that pushed you over the threshold
- The CRA can assess GST/HST on all taxable supplies from that effective date
- If you did not collect GST/HST from clients after that date, you still owe it — it comes out of your revenue
- Interest accrues on any uncollected GST/HST from the date each supply was made
For example: You cross $30,000 on March 15 and should have registered by April 13. You keep working and invoicing without GST/HST through June 30. When you finally register in July, the CRA can assess GST/HST on everything from approximately April 13 onward — regardless of whether you collected it.
How to Handle Late Registration
Step 1: Register immediately through BRO
Register for a GST/HST account through the CRA Business Registration Online (BRO) portal at canada.ca. This is now the only registration channel — phone registrations are no longer accepted (effective November 3, 2025).
Step 2: Determine your effective date
Identify the date you crossed the $30,000 threshold. This is when GST/HST should have been charged. The 29-day window from that date is when registration was required.
Step 3: Calculate retroactive GST/HST
For all taxable supplies made after your effective registration date, calculate the GST/HST that should have been collected. For example, if you invoiced $20,000 to Ontario clients after the effective date, you owe $20,000 × 13/113 = $2,301 in HST (the portion of the total that would have been tax if you had charged it).
Step 4: File a return covering the retroactive period
Your first GST/HST return will cover the period from your effective registration date to your first period end. Include the retroactive GST/HST owing and any ITCs you can claim for that period.
Step 5: Consider Voluntary Disclosure
If you have been unregistered for a long period (6+ months) with significant taxable supplies, a Voluntary Disclosure application may reduce penalties. The VDP allows you to come forward proactively and negotiate reduced interest. A CPA handles VDP submissions.
Can You Bill Clients Retroactively for GST/HST?
Technically yes — but practically difficult. You can issue amended invoices to clients for the GST/HST that should have been charged. Whether clients will pay is another matter. For ongoing client relationships, some clients will accommodate this; others will not. If clients refuse, the GST/HST shortfall is your obligation.
Frequently Asked Questions
What if I just never noticed I crossed $30,000 — does the CRA know?
The CRA cross-references T4A information returns, bank deposit patterns (for businesses audited), and revenue patterns from other registrants in the same industry. For many freelancers, late registration goes undetected indefinitely. But if you are ever audited, retroactive assessment is standard. Registering as soon as you realize you should have is the right course of action.
Does registering late affect my ability to claim ITCs retroactively?
Yes. Once registered, you can claim ITCs for business purchases made during the retroactive registration period (the period between your effective date and your actual registration). Keep receipts from that entire period — you may be entitled to ITCs on purchases made before you formally registered.
What is the statute of limitations on the CRA assessing late GST/HST?
The CRA can generally assess GST/HST within 4 years of the date a return was due or filed. For fraud or gross negligence, there is no limitation period. Register proactively — the longer the exposure period, the greater the potential retroactive assessment.